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D04155GE Due to the height and steepness of the talus slopes at this site we do not feel that there is a technically viable concept to mitigate the observed conditions. We do feel that there are some cautionary steps that can be taken to reduce the potential for the public to be exposed to hazardous conditions. The current use of the area is for material and equipment storage for the San Juan County Road Department and is closed to the public. Evidence of limited rockfall activity was observed at the site, therefore we feel that the area along the toe of the slope should remain closed to the public. We suggest that a berm and rock catchment trench be constructed along the toe of the slope to reduce the potential for rocks striking stored equipment and materials at the site. The trench should be about ten (10) feet wide with a berm about eight (8) to ten (10) feet tall. The trench should be constructed so that water does not accumulate in the bottom of the trench. The slopes of the berm should have inclinations of about two to one (2:1, horizontal to vertical) and flatter. The material within the berm should be moisture conditioned and compacted to at least ninety (90) percent of maximum dry density as defined by ASTM D1557, modified Proctor test. Although we feel that it is relatively unlikely that a rapid catastrophic failure of the slope supporting / the roadway will occur, we do feel that it is prudent to place warning signs above and below the // subject area to warn travelers of a potential for rapid failure of the roadway support materials. 5.0 POST DESIGN CONSIDERATIONS The project geotechnical engineer should be consulted during construction ofthe project to observe ~p site conditions and open excavations during construction and to provide materials testing of soil during the berm construction. This subsurface soil and foundation condition study is based on limited sampling; therefore, it is necessary to assume that the subsurface conditions do not vary greatly from those encountered in the field study. Our experience has shown that significant variations are likely to exist and can become appazent only during additional on site excavation. For this reason, and because of our familiarity with the project, Lambert and Associates should be retained to observe foundation excavations prior to foundation construction, to observe the geotechnical engineering aspects of the construction and to be available in the event any unusual or unexpected conditions aze encountered. The cost of the geotechnical engineering observations and material testing during construction or additional engineering consultation is not included in the fee for this report. We recommend that your construction budget include site visits early during construction schedule for the project geotechnical engineer to observe foundation excavations and for additional site visits to test compacted soil. We recommend that the observation and material testing services during construction be retained by the owner or the owner's engineer or architect, not the contractor, to maintain third party credibility. We aze experienced and available to provide material testing services. We have included a copy of a ~rit~TEl'~ ~[lt~l ~1j38IIx:TfXfEB CONSULTING GEOTECHNICAL ENGINEERS AND -t4- MATERIALS TESTING